Modification of the MCS Claims Processing System Logic for Modifier 59, XE, XS, XP, and XU Involving the National Correct Coding Initiative (NCCI) Procedure to Procedure (PTP) Column One and Column Two Codes.Modifiers 59, XE, XS, XP, and XU are among the NCCI-associated modifiers. The Multi-Carrier System (MCS) currently requires that modifiers 59, XE, XS, XP, or XU be appended to the column two code of a PTP edit to bypass the edit. With the implementation of CR 11168,"Medicare will allow modifiers 59, XE, XS, XP, or XU on column one and column two codes to bypass the edit''.Source: Modifier 59 Changes in PTP editsClick Here for Example